Symptoms

In systems running Ubuntu 18.04 with NVIDIA graphics users may experience X Server crashes when DisplayLink device is connected before the X Server starts. This
applies to systems using an NVIDIA-only GPU setup, or a combination of integrated
Intel GPU and a discrete NVIDIA GPU.

On affected platforms, some or all of the following issues can be observed:

System
crashes during logout with DisplayLink device plugged in.

It is
impossible to log in with DisplayLink device plugged in.

Workaround: Switch XServer DDX driver to modesetting

To workaround that issue, it is necessary to force using
modesetting driver globally, for all GPUs.